Redis [BUG] redis-benchmark --cluster doesn't support ipv6

Describe the bug Hi, I'm trying to run redis-benchmark with cluster option and getting this error:

redis-benchmark -h SHARD_URI -a PASSWORD  --cluster
Cluster has 6 master nodes:

Master 0: 0ba80fdb77300de637600ef6497da252dd1274e8 2a02:6
Could not connect to Redis at 2a02:6: Name or service not known
WARN: could not fetch node CONFIG 2a02:6
Master 1: c1a83816a940c8401fef4eb618b2f60e92831316 2a02:6
Could not connect to Redis at 2a02:6: Name or service not known
WARN: could not fetch node CONFIG 2a02:6
Master 2: 4666482d50faf41fef1765b4459688bc919c4efa 2a02:6
Could not connect to Redis at 2a02:6: Name or service not known
WARN: could not fetch node CONFIG 2a02:6
Master 3: 3ad940e830055faab65febbe5e1e7e796be42a81 2a02:6
Could not connect to Redis at 2a02:6: Name or service not known
WARN: could not fetch node CONFIG 2a02:6
Master 4: d00cc077bcaab64caf7104d1567354171099ba15 2a02:6
Could not connect to Redis at 2a02:6: Name or service not known
WARN: could not fetch node CONFIG 2a02:6
Master 5: 2e8968388b944dbdb6dc399920ed836b94c0ded4 2a02:6
Could not connect to Redis at 2a02:6: Name or service not known
WARN: could not fetch node CONFIG 2a02:6

To reproduce

Run redis-benchmark -h SHARD_URI -a PASSWORD --cluster with a cluster where Redis hosts have ipv6-addresses only.

Expected behavior

redis-benchmark runs against all cluster shardes.

Additional information

$ redis-benchmark -v
redis-benchmark 6.2.6